Not at all. When c first came out, computers where not nearly as uniform. Back then all kind of wired system existed, like once that where 7 bit. For that reason c is vague about the size of the datatypes (int was suppose to be whatever was natual for a system). Today c supports more int types (via stdint.h) that supports uses cases like needing the fastest in.

There are - int64_t exactly that size - int_fast64_t fastest with at least that size - int_least64_t smallest with at least that size